There are two good Android apps that are going through some rapid development right now. Both have very responsive developers so it might be easier to get your requests into those than to create your own. GTD DGT has a DGT SODA beta group on Google+ that's working on a complete redesign of the app. MyToodle also has a beta group on G+ that gets early releases & provides feedback on features to be added.

I'd recommend you check both of those apps/groups out before you start writing your own!